1. Field of the Invention
The present invention relates to an image processing method and apparatus and, more particularly, to an image processing method and apparatus in which the virtual storage concept is used for the storage and management of image data to perform image processing.
2. Description of the Prior Art
Generally, in image processing, image data displayed with pixels, such as characters, patterns, etc., are processed. Therefore, image processing ordinarily must handle an enormous amount of data, and accordingly, it is quite time consuming.
Japanese Patent Unexamined Published Application No. 59-212,971 discloses an image data generator wherein the processing time for generating image data may be reduced by reusing image data which has been generated and retained as much as possible in an external storage. This application also discloses that if the capacity of external storage would be exceeded when newly generated image data is stored in it, the newly generated image data could be stored in external storage by removing image data already stored in external storage in an ascending order of frequency of use.
Japanese Patent Unexamined Published Application No. 58-4,470 discloses that only necessary portions of image data in a memory are fetched sequentially from the top into a buffer or a CPU in the form of blocks.
In processing image data with a data processing system having a small storage capacity, for example, a personal computer, the size of an image processing program used is limited because of the enormous amount of image data. The restriction would be removed by storing and retaining the image data in external storage.
However, in such a system as disclosed in the above Application No. 59-212,971, the efficiency in handling the image data and, therefore, the performance of the image processing is reduced, since the time required to transfer the image data to and from external storage occupies most of the image processing time. It is therefore necessary to reduce this time.
Accordingly, as disclosed in the above mentioned Application No. 58-4,470, attempts have been made to reduce the time required to transfer image data by transferring the image data in the form of blocks. However, in that system, the data blocks are fetched only sequentially from the top, and such a procedure could not be adapted to complex image processing, such as COPY and ROTATE processing. Therefore, the performance of complex image processing must be reduced, otherwise it becomes infeasible.
It is thus an object of the present invention to provide an image processing method and system wherein the virtual storage concept is introduced into the storage and management of image data so as to be adapted to an image processing.
In accordance with the present invention, an image processing method and system, wherein the storage and management of image data have been improved is provided. Accordingly, the present invention can substantially improve the performance of image processing compared with conventional image processing methods and systems.
These and other objects, advantages and features of the invention will be more apparent upon reference to the following specification and the annexed drawings.